U.S. patent number 5,135,001 [Application Number 07/622,513] was granted by the patent office on 1992-08-04 for ultrasound sheath for medical diagnostic instruments.
This patent grant is currently assigned to C. R. Bard, Inc.. Invention is credited to Edward L. Sinofsky, Barry D. Weitzner.
United States Patent |
5,135,001 |
Sinofsky , et al. |
August 4, 1992 |
Ultrasound sheath for medical diagnostic instruments
Abstract
A flexible disposable ultrasound transducer sheath for medical
diagnostic instruments comprises a core having a central opening
aligned to a core axis and contoured and dimensioned in cross
section in correspondence with the cross section of a standard
instrument shaft where the transducer is to be removably applied. A
piezoelectric layer of flexible polyvinylidene fluoride is formed
over the core and a first electrically conductive gold layer
electrode is sandwiched between the piezoelectric layer and the
outer core surface. A second conductive layer is formed over the
piezoelectric layer and includes a plurality of conductive gold
strip electrodes aligned with the axis of the core, the strips
being separated one from the other circumferentially. The
transducer, when driven with electrical pulses, is an ultrasound
emitter. As a receiver, the transducer converts returning echoes
into electrical signals. Alternative embodiments include inflatable
balloons over the transducer or as an element of the
transducer.
Inventors: |
Sinofsky; Edward L. (Peabody,
MA), Weitzner; Barry D. (Chelmsford, MA) |
Assignee: |
C. R. Bard, Inc. (Murray Hill,
NJ)
|
Family
ID: |
24494454 |
Appl.
No.: |
07/622,513 |
Filed: |
December 5, 1990 |
Current U.S.
Class: |
600/459;
600/462 |
Current CPC
Class: |
A61B
8/12 (20130101); A61B 8/445 (20130101) |
Current International
Class: |
A61B
8/12 (20060101); A61B 008/14 () |
Field of
Search: |
;128/662.03,662.06,662.04 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
|
WO89/04143 |
|
May 1989 |
|
EP |
|
2157828A |
|
Oct 1985 |
|
GB |
|
2208138 |
|
Mar 1989 |
|
GB |
|
Primary Examiner: Jaworski; Francis
Assistant Examiner: Manuel; George
Attorney, Agent or Firm: Darby and Darby
Claims
We claim:
1. A disposable ultrasound transducer sheath for removable
attachment at a particular location to the external surface of the
shaft of a medical diagnostic instrument, comprising:
a cylindrical core having a central opening and an outer surface
aligned to a core axis, said central opening being contoured and
dimensioned in cross sections in correspondence with and for
substantially encircling the external surface of said shaft at said
particular location, said core being electrically
non-conductive;
a cylindrical piezoelectric layer having an inner surface and an
outer surface formed over and substantially encircling said core
outer surface;
a first electrically conductive layer sandwiched between said
piezoelectric layer and said outer surface of said core, said first
conductive layer being in surface contact with and substantially
encircling said core outer surface and being in surface contact
with said piezoelectric layer inner surface; and
a second conductive layer formed over said piezoelectric layer,
said second conductive layer being in surface contact with and
substantially encircling said outer surface of said piezoelectric
layer.
2. A disposable ultrasound transducer sheath as in claim 1, wherein
said piezoelectric layer is at least one of resilient and
flexible.
3. A disposable ultrasound transducer sheath as in claim 2, wherein
one of said first and second conductive layers substantially
continuously contacts the adjacent piezoelectric layer surface and
the other one of said first and second conductive layers includes a
plurality of conductive strips aligned with said axis and separated
one from the other, said conductive strips being in contact with
said piezoelectric layer.
4. A disposable ultrasound transducer sheath as in claim 1, wherein
said piezoelectric element is formed of polyvinylidene
fluoride.
5. A disposable ultrasound transducer sheath as in claim 1, wherein
said conductive layers are formed of gold.
6. A disposable ultrasound transducer sheath as in claim 3, and
further comprising electrical leads extending respectively from
said conductive layers, each said conductive strip being connected
to an electrical lead.
7. A disposable ultrasound transducer sheath as in claim 1, wherein
the interface between said piezoelectric layer and said first
conductive layer and core is acoustically reflective.
8. A disposable ultrasound transducer sheath for removable
attachment at a particular location to the shaft of a medical
diagnostic instrument, comprising:
a core having a central opening and an outer surface aligned to a
core axis, said central opening being contoured and dimensioned in
cross sections in correspondence with the cross section of said
shaft at said particular location, said core being electrically
non-conductive;
a piezoelectric layer having an inner surface and a outer surface
formed over said core outer surface, said piezoelectric layer being
in the order of approximately 5 to 15 microns in thickness;
a first electrically conductive layer sandwiched between said
piezoelectric layer and said outer surface of said core, said first
conductive layer being in surface contact with said core outer
surface and with said piezoelectric layer inner surface; and
a second conductive layer formed over said piezoelectric layer,
said second conductive layer being in surface contact with said
outer surface of said piezoelectric layer.
9. A disposable ultrasound transducer sheath for removable
attachment at a particular location to the shaft of a medical
diagnostic instrument, comprising:
a core having a central opening and an outer surface aligned to a
core axis, said central opening being contoured and dimensioned in
cross sections in correspondence with the cross section of said
shaft at said particular location, said core being electrically
non-conductive, said core being dimensioned to fit onto said shaft
at said particular location with a tight frictional fit between
them;
a piezoelectric layer having an inner surface and a outer surface
formed over said core outer surface;
a first electrically conductive layer sandwiched between said
piezoelectric layer and said outer surface of said core, said first
conductive layer being in surface contact with said core outer
surface and with said piezoelectric layer inner surface; and
a second conductive layer formed over said piezoelectric layer,
said second conductive layer being in surface contact with said
outer surface of said piezoelectric layer.
10. A disposable ultrasound transducer sheath for removable
attachment at a particular location to the shaft of a medical
diagnostic instrument, comprising:
a core having a central opening and an outer surface aligned to a
core axis, said central opening being contoured and dimensioned in
cross sections in correspondence with the cross section of said
shaft at said particular location, said core being electrically
non-conductive;
a piezoelectric layer having an inner surface and a outer surface
formed over said core outer surface;
a first electrically conductive layer sandwiched between said
piezoelectric layer and said outer surface of said core, said first
conductive layer being in surface contact with said core outer
surface and with said piezoelectric layer inner surface;
a second conductive layer formed over said piezoelectric layer,
said second conductive layer being in surface contact with said
outer surface of said piezoelectric layer; and
an elastic cuff extending axially from at lest one of said core and
said piezoelectric layer, said cuff being subject to elastically
stretching when said transducer is positioned on said instrument
shaft at said particular location, said elastic stretching bringing
said cuff into compressive contact with said shaft, thereby holding
said transducer in place.
11. A disposable ultrasound transducer sheath for removable
attachment at a particular location to the shaft of a medical
diagnostic instrument, comprising:
a core having a central opening and an outer surface aligned to a
core axis, said central opening being contoured and dimensioned in
cross sections in correspondence with the cross section of said
shaft at said particular location, said core being electrically
non-conductive;
a piezoelectric layer having an inner surface and a outer surface
formed over said core outer surface;
a first electrically conductive layer sandwiched between said
piezoelectric layer and said outer surface of said core, said first
conductive layer being in surface contact with said core outer
surface and with said piezoelectric layer inner surface;
a second conductive layer formed over said piezoelectric layer,
said second conductive layer being in surface contact with said
outer surface of said piezoelectric layer;
a cuff extending axially from at least one of said core and
piezoelectric layer, said cuff being subject to at least partially
encircling said instrument shaft when said transducer is applied to
said instrument, and
an elastic band for overlying said cuff, said band being subject to
elastically stretching when said band is positioned over said cuff
on said transducer when said transducer is positioned at said
particular location on said instrument shaft, said elastic
stretching bringing said cuff into compressive contact with said
shaft, thereby holding said transducer in place.
12. A disposable ultrasound transducer sheath for removable
attachment at a particular location to the shaft of a medical
diagnostic instrument, comprising:
a core having a central opening and an outer surface aligned to a
core axis, said central opening being contoured and dimensioned in
cross sections in correspondence with the cross section of said
shaft at said particular location, said core being electrically
non-conductive and having a thickness in the range of 150 to 250
microns,
a piezoelectric layer having an inner surface and a outer surface
formed over said core outer surface;
a first electrically conductive layer sandwiched between said
piezoelectric layer and said outer surface of said core, said first
conductive layer being in surface contact with said core outer
surface and with said piezoelectric layer inner surface; and
a second conductive layer formed over said piezoelectric layer,
said second conductive layer being in surface contact with said
outer surface of said piezoelectric layer.
13. A disposable ultrasound transducer sheath for removable
attachment at a particular location to the shaft of a medical
diagnostic instrument, comprising:
a core having a central opening and an outer surface aligned to a
core axis, said central opening being contoured and dimensioned in
cross sections in correspondence with the cross section of said
shaft at said particular location, said core being electrically
non-conductive;
a piezoelectric layer having an inner surface and a outer surface
formed over said core outer surface;
a first electrically conductive layer sandwiched between said
piezoelectric layer and said outer surface of said core, said first
conductive layer being in surface contact with said core outer
surface and with said piezoelectric layer inner surface;
a second conductive layer formed over said piezoelectric layer,
said second conductive layer being in surface contact with said
outer surface of said piezoelectric layer; and
a reversibly inflatable balloon coaxially surrounding said
transducer.
14. A disposable ultrasound transducer sheath for removable
attachment at a particular location to the shaft of a medical
diagnostic instrument, comprising:
an annular piezoelectric layer having an inner and outer surface
aligned to an axis, said piezoelectric layer being at least one of
resilient and flexible;
a first electrically conductive layer in surface contact with said
piezoelectric layer inner surface; and
a second conductive layer formed over said piezoelectric layer,
said second conductive layer being in surface contact with said
outer surface of said piezoelectric layer, one of said first and
second conductive layers substantially continuously contacting the
adjacent piezoelectric layer surface, and the other one of said
conductive first and second layers includes a plurality of
conductive strips aligned with said axis and separated one from the
other, said conductive strips being in contact with said
piezoelectric layer.
15. A disposable ultrasound transducer sheath as in claim 14,
wherein said piezoelectric element is formed of polyvinylidene
fluoride.
16. A disposable ultrasound transducer sheath as in claim 15,
wherein said conductive layers are formed of gold.
17. A disposable ultrasound transducer sheath as in claim 14,
wherein said conductive layers are formed of gold.
18. A disposable ultrasound transducer sheath as in claim 14,
wherein said piezoelectric layer in the order of approximately 5 to
15 microns in thickness.
19. A disposable ultrasound transducer sheath as in claim 14,
wherein the interface between said piezoelectric layer and said
first conductive layer is acoustically reflective.
20. A disposable ultrasound transducer sheath as in claim 14, and
further comprising an elastic cuff extending axially from said
piezoelectric layer, said cuff being subject to elastically
stretching when said transducer is positioned on said instrument
shaft at said particular location, said elastic stretching bringing
said cuff into compressive contact with said shaft, thereby holding
said transducer in place.
21. A disposable ultrasound transducer sheath as in claim 14, and
further comprising a cuff extending axially from said piezoelectric
layer, said cuff being subject to at least partially encircling
said instrument shaft when said transducer is applied to said
instrument, and further comprising an elastic band for overlying
said cuff, said band being subject to elastically stretching when
said band is positioned over said cuff when said transducer is
positioned at said particular location on said instrument shaft,
said elastic stretching bringing said cuff into compressive contact
with said shaft, thereby holding said transducer in place.
22. A disposable ultrasound transducer sheath as in claim 14, and
further comprising a reversible inflatable balloon coaxially
surrounding said transducer.
23. A disposable ultrasound transducer sheath for removable
attachment at a particular location to the shaft of a medical
diagnostic instrument, comprising:
an annular piezoelectric layer having an inner and an outer surface
aligned to an axis;
a first electrically conductive layer in surface contact with said
piezoelectric layer inner surface;
a reversibly inflatable balloon coaxially surrounding the outer
surface of said piezoelectric layer; and
a second conductive layer formed over said inflatable balloon, said
second conductive layer being in surface contact with the outer
surface of said balloon.
24. A disposable ultrasound transducer sheath as in claim 23,
wherein one of said conductive layers is a continuous surface of
the other said conductive layer is a plurality of conductive strips
aligned with said axis and separated one from the other.
25. A disposable ultrasound transducer sheath as in claim 24,
further comprising electrical leads extending respectively from
said conductive layers, each said conductive strip being connected
to an electrical lead.
26. A disposable ultrasound transducer sheath for removable
attachment at a particular location to the shaft of a medical
diagnostic instrument, comprising:
a core having a central opening and an outer surface aligned to a
core axis, said central opening being contoured and dimensioned in
cross sections for correspondence with the cross section of said
shaft at said particular location, said core being electrically
non-conductive;
a piezoelectric layer having an inner surface and a outer surface
formed over said core outer surface, said piezoelectric layer being
at least one of resilient and flexible;
a first electrically conductive layer sandwiched between said
piezoelectric layer and said outer surface of said core, said first
conductive layer being in surface contact with said core outer
surface and with said piezoelectric layer inner surface;
a second conductive layer formed over said piezoelectric layer,
said second conductive layer being in surface contact with said
outer surface of said piezoelectric layer, one of said first and
second conductive layers substantially continuously contacts the
adjacent piezoelectric layer surface and the other one of said
first and second conductive layers includes a plurality of
conductive strips aligned with said axis and separated one from the
other, said conductive strips being in contact with said
piezoelectric layer;
electrical leads extending respectively from said conductive
layers, each said conductive strip being connected to an electrical
lead.
27. A disposable transducer for removable attachment at a
particular location to the external surface of the shaft of a
medical diagnostic instrument, comprising:
a transducer unit including a transducer, said transducer unit
being dimensioned to rest, in use, on a particular location of said
shaft surface;
an elastic cuff extending from said transducer unit, said cuff
being an elastic loop and subject to stretching in use to encircle
said instrument shaft proximate said particular location, said
elastic stretching bringing said cuff into compressive contact with
said shaft, thereby holding said transducer in place.
28. A disposable transducer for removable attachment at a
particular location to the external surface of the shaft of a
medical diagnostic instrument, comprising:
a transducer unit including a transducer, said transducer unit
being dimensioned to rest, in use, on a particular location of said
shaft surface;
a cuff extending from said transducer unit, said cuff in use of
said instrument being subject to at least partially encircling said
instrument shaft;
an elastic band for overlying said cuff, said band being subject to
elastic stretching when sand band is positioned over said cuff when
said transducer is positioned at said particular location on said
instrument shaft, said elastic stretching of said band bringing
said cuff into compressive contact with said shaft, thereby holding
said transducer in place.
Description
FIELD OF THE INVENTION
This invention relates generally to instruments that can be
inserted into body lumens or cavities, and more particularly to
instruments having capability for ultrasound imaging.
BACKGROUND OF THE INVENTION
Ultrasound energy is commonly used for imaging of internal body
structures. Endoscopes are used for visual inspection of internal
organs of living bodies. Endoscopes and catheters incorporating
ultrasound transducers are well known. The instruments typically
include a flexible tube that extends between a control housing at
the proximal end and a probe at its distal end. The probe is
controlled by an operator, and illumination and viewing means are
usually provided in the system.
When optical means are used to view the interior surfaces of the
body cavities through which the endoscope passes, the operator
receives information concerning only interior surface conditions.
Ultrasonics provide subsurface imaging information of underlying
structure and interior organs. Thus, it is desirable to have both
optical viewing and ultrasonic information at a desired location
within a patient's body.
However, many current ultrasound devices may require that other
functions, for example, the viewing function, be compromised to
accommodate the ultrasound function. The increased costs and the
possibility of interfering with an existing instrument capability
by the combination with ultrasound imaging are two factors that
have tended to limit usage of instruments with ultrasound imaging
capability. Nevertheless, instruments lacking ultrasonic capability
have little relative value when compared to a similar instrument
with ultrasound capability. Therefore, upgrading is desirable for
many existing instruments now lacking ultrasound capability.
It would be advantageous to have an ultrasonic imaging capability
even when the instrument is otherwise a non-electrical device. For
example, conventional catheters and dilators would be good vehicles
for the addition of ultrasound capability.
What is needed is a low cost device for adding ultrasound imaging
capability to existing instruments now used, without imaging, to
perform diagnostic functions within body cavities.
BRIEF DESCRIPTION OF THE INVENTION
Accordingly, an object of the invention is to provide an improved
ultrasound sheath for attachment to medical diagnostic instruments,
enabling performance of an additional function.
Another object of the invention is to provide an improved
ultrasound sheath for medical diagnostic instruments that can be
added to existing diagnostic instruments without alterations of the
initial device.
Still another object of the invention is to provide an improved
ultrasound sheath for medical diagnostic instruments that is
disposable after use and economical to produce and utilize.
Yet another object of the invention is to provide an improved
ultrasound sheath for medical diagnostic instrument, that is
combinable with existing endoscopes, catheters, dilators, and the
like.
In a preferred embodiment of an ultrasound sheath for medical
diagnostic instruments in accordance with the invention, the
transducer comprises a core having a central opening aligned to a
core axis. The central opening is contoured and dimensioned in
cross section transverse to the axis in correspondence with the
cross section of the instrument shaft where the transducer is to be
applied. A resilient piezoelectric layer is formed over the core
and a first electrically conductive gold layer is sandwiched
between the piezoelectric layer and the outer surface of the core.
The first conductive layer makes good surface contact with both the
core and the piezoelectric layer. A second conductive layer is
formed over the outside of the piezoelectric layer and includes a
plurality of conductive gold strips aligned with the axis of the
core, the strips being separated one from the other
circumferentially. The transducer when driven with electrical
pulses, is an ultrasound emitter. As a receiver, the transducer
converts returning echoes into electrical signals.
Alternative embodiments in accordance with the invention include
inflatable balloons over the transducer or as an element of the
transducer. When the diagnostic instrument is properly positioned
in the body of a subject, the balloon is inflated to provide better
contact and more efficient energy transmission between the
transducer and the body tissues.
Further objects and advantages of the invention will be apparent
from the specification and drawings. The invention accordingly,
comprises the features of construction, combination of elements,
and arrangement of parts that will be exemplified in the
constructions hereinafter set forth, and the scope of the invention
will be indicated in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
For a fuller understanding of the invention, reference is had to
the following description taken in connection with the accompanying
drawings, in which:
FIG. 1, is a perspective view of an ultrasound sheath for medical
diagnostic instruments in accordance with the invention, applied to
an endoscope;
FIG. 2, is a sectional view to an enlarged scale taken along the
line 2--2 of FIG. 1;
FIG. 3, is an alternative embodiment of an ultrasound sheath for
medical diagnostic instruments in accordance with the invention
including a fluid-filled balloon;
FIG. 4, is another alternative embodiment of an ultrasound sheath
for medical diagnostic instruments in accordance with the invention
including an inflatable balloon;
FIG. 5, is a view similar to FIG. 1, of an alternative embodiment
of an ultrasound sheath for medical diagnostic instruments in
accordance with the invention;
FIG. 6, is still another alternative embodiment in accordance with
the invention of an ultrasound sheath for medical diagnostic
instruments; and
FIG. 7, illustrates a catheter including an ultrasound sheath for
medical diagnostic instruments in accordance with the invention as
applied to an endoscope.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
With regard to FIG. 1, and ultrasound sheath 10 in accordance with
the invention includes an electrically insulating cylindrical core
11 having a thin layer 12 of gold and an overlying flexible
piezoelectric element 14 formed thereon, the core 11, gold layer 12
and piezoelectric element 14 being substantially coaxial and
coextensive.
A plurality of gold electrodes 16 are formed on the outer surface
of the piezoelectric element 14 and extend generally parallel to
the longitudinal axis 18 of the core 11. The electrodes 16 are
spaced apart circumferentially, with each electrode 16
approximately the same distance from the adjacent electrodes. It
should be understood that in an alternative embodiment of the
sheath 10, circumferential spacing may not be uniform so as to
obtain desired directional effects, and the lengths of the
electrodes 16 on the piezoelectric element 14 may also not be
uniform.
A plurality of leads 20, electrical conductors, extend from one end
of the sheath 10. A single lead 20 connects to each longitudinal
electrode 16 and to the gold layer 12 such that an electrical
potential may be applied between the cylindrical ground electrode
12 and each longitudinal electrode 16, respectively. In use, the
electrical signals are provided and processed by external
electronic circuits and devices (not shown) that are known in the
art. Similarly, techniques for attaching fine leads to such thin
electrodes are also well known.
It is a well-known phenomenon that the piezoelectric material 14 is
elastically distorted, that is, changed dimensionally, when an
electric potential is applied across the piezoelectric material 14.
A voltage applied between any single longitudinal electrode 16 and
the gold layer 12 creates a local distortion in the piezoelectric
material 14, which distortion is released when the voltage is
removed. Any number of longitudinal electrodes 16 can be connected
simultaneously to the source of electrical voltage. When all of the
electrodes 16 are simultaneously powered, an omnidirectional
acoustic output is provided. Directionally lobed outputs can be
provided by selection of the electrodes 16 that are powered, and
their sequence of energization.
Pulsing of the electrodes 16 provides a physical output of the same
fundamental frequency as the energizing pulses. Waves of ultrasonic
energy are directed radially outward from the longitudinal axis 18.
The relative rigidities of the internal core 11, the endoscope to
which the sheath 10 is applied, and the elastic, resilient
piezoelectric material 14, assure that substantially all of the
ultrasonic energy is reflected at the core/electrode interface with
the resilient piezoelectric material and directed radially
outward.
The electrodes 12, 16, may be formed on the cylinder of
piezoelectric material 14 by conventional techniques, for example,
vapor deposition or sputtering, and the spaces between the
longitudinal electrodes 16 can be formed, for example, by ablating
portions of the outer surface with a laser beam.
The inside diameter of the core 11 is selected to provide a
precision fit on the body or shaft of a standard endoscope 22, or
the shaft of any other instrument, for example, a dilator,
catheter, etc. To add an ultrasonic capability to the conventional
endoscope, the sheath 10 is slid along the cylindrical shaft 24 of
the endoscope 22 using, for example, water on the surface as a
lubricant. In the process of positioning the sheath 10, the sheath
may be rotated about the axis 18, to achieve the desired alignment
relative t the tip of the instrument. Because the endoscope is
flexible to allow bending, it is necessary that the sheath 10 also
be bendably flexible. The very thinness of the layers 11, 12, 14,
16 as discussed hereinafter produces the required bendability
although the core and electrode materials, if considerably thicker,
would be considered to be rigid materials.
Further, although the sheaths illustrated in the figures have axial
lengths 1 greater than their diameters d, it should be understood
that in alternative embodiments in accordance with the invention,
the axial length of a sheath may be equal to or less than the
diameter. Reducing the 1/d ratio improves the ability of the sheath
to bend with the endoscope shaft in use and in application of the
sheath to the instrument.
The piezoelectric element 14 may be formed of a resilient
composition of polyvinylidene fluoride (PVDF), which is a known
piezoelectric polymer when prepared in a known manner, for example,
in an electric field at elevated temperature. As is well known,
piezoelectric elements when driven by electrical impulses are
emitters of sonic energy. On the other hand, forces acting on the
surface of the piezoelectric element induce distortions that in
turn induce measurable electrical potentials between the ground
electrode 12 and the longitudinal electrodes 16. Thus, a sheath 10
that serves as an ultrasound emitter can also be adapted
electronically for receiving returning echoes of the emitted
sounds. Control of emitting frequencies, for example, in the order
of 40 MHz, and pulse width to achieve desired image resolutions,
are techniques well known in the ultrasonic instrumentation
arts.
The sheath 10 is very thin and therefore is flexible even though,
as stated, the core 11 and gold electrodes, if much thicker, might
be considered as rigid. The sheath 10 is readily removed from the
endoscope 22, e.g., by peeling and cutting, for replacement with
another sheath 10. Mounting the sheath 10 on the shaft 24 of the
endoscope 22, provides a rigid backing for the piezoelectric
emitter/receiver and further assures efficient outward energy
emission and reception with minimal energy loss. Thus, a disposable
ultrasound device and ultrasound capability are provided for
application to conventional endoscopes. The sheaths are produced
economically using known techniques as indicated above.
The resilient piezoelectric layer 14 may have a thickness in the
range of 5 to 15 microns. The core, which may be fabricated of
vinyl, polyethylene, polyurethane, and the like, has a thickness in
the range of 150 to 250 microns, and the gold electrodes may have a
thickness less than a micron.
FIG. 3, illustrates the ultrasonic sheath 10 of FIG. 1, to which is
attached an inflatable balloon 26. After the endoscope 22 is
positioned within the subject's body at the desired location with
the balloon 26 deflated, the balloon 26 is filled with liquid by
known techniques such that good contact is made between the outside
surface of the balloon 26 and the internal surfaces 28 of the
living body. Such firm contact between the balloon and the body
surfaces 28 assures more efficient transmission and echo reception
of ultrasound energy at the sheath 10 than would be provided when
gaps and spaces exist between the ultrasound sheath and the body
tissues.
FIG. 4 illustrates an ultrasonic sheath 10' that is similar to the
sheaths 10 of FIGS. 1-3. In this embodiment in accordance with the
invention, the longitudinal electrodes 16' are mounted on the
outside surface of a balloon 26'. The balloon 26' envelops the
central cylindrical gold electrode 12 and piezoelectric element 14
(not shown in FIG. 4). As in the other embodiments, electrical
leads (not shown) connect to each longitudinal electrode 16' so
that ultrasonic emission and reception is achieved, as described
above. The endoscope 22 is inserted within the body with the
balloon 26' deflated. The balloon 26' is inflated at the desired
body location to provide good surface contact and efficient
transmission and reception of ultrasonic energy. In ,an alternative
embodiment, the electrodes 16' may be on the inside surface of the
balloon 26'.
It should be understood that in alternative embodiments in
accordance with the invention, the longitudinal strip electrodes 16
and continuous cylinder electrodes 12 ca be reversed in position,
that is, the electrodes 16 are positioned closer to the endoscope
22 and the continuous cylindrical electrode 12 is away from the
endoscope shaft 24. Further, the electrode 12 may also be divided
into separated strips, segments, and the like. The electrodes 12,
16 may also be divided in the longitudinal direction and in
patterns to suit a desired objective. Each electrode segment in use
is connected by a lead directly or indirectly to a driving signal
generating/data processing system external to the human body.
In FIG. 5, a sheath 30 is similar to the sheath 10 of FIGS. 1 and
2, with the addition of flexible cuffs 32, having resilience and a
greater flexibility than the piezoelectric element 14. By known
techniques, for example, double injection molding, such cuffs 32 of
greater resilience and elasticity than the combined core and
transducing layers 12, 14, 16 of the sheath 30, may be provided.
The unstressed internal diameter of the cuffs 32 is smaller than
the shaft diameter of the endoscope 22, such that in sliding the
sheath 30 onto the endoscope 22, a very tight fit is achieved
between the cuffs 32 and the shaft 24. A precision fit is not
required between the core 11 and the shaft 24. As stated, the
relative rigidity of the internal core and inner electrode 12
assures efficient outward radiation of ultrasonic energy and
efficient reception of returning echoes, without undue absorption
losses.
In FIG. 6, a sheath 40, which is similar to the sheath 30 of FIG.
5, is fitted with cuffs 32 that extend from both ends of the active
transducer portion. A separate elastic band 42 is placed over the
cuff, which may be elastic or inelastic. The elastic band 42
overlays the end of the cuff 32 and also extends to overlay a
portion of the shaft 24 of the endoscope 22. The elastic band 42 is
stretched to fit on the shaft 24 and over the cuff 32 such that
when released, the elastic band 42 contracts and tightly holds the
sheath 40 in position o the shaft 24. An elastic band 42 is used on
one or both longitudinal ends of the sheath 40.
In each embodiment of FIGS. 5 and 6, the balloon alternatives may
also be applied as illustrated in FIGS. 3 and 4. In each
embodiment, the sheath is attachable to a standard endoscope shaft
and is removable and disposable. The transducer may be manufactured
inexpensively by known techniques, and disposal of the ultrasonic
sheath after use presents no economic hardship. More elemental
prior art instruments are easily and economically upgraded with
ultrasound capability.
FIG. 7 illustrates an ultrasonic sheath 10 mounted on a shaft 44
that is extendible from the working channel 46 of an endoscope 48.
The endoscope also includes an optical detector 50 and light
sources 52. The sheath 10 used in the endoscope 48 may also be
fitted with a balloon as illustrated in FIGS. 3 and 4.
Whereas the electrodes are described above as being gold, other
electrically conductive materials compatible with usage within the
body may be used.
In another alternative embodiment (not shown), the core 11 is
omitted. The two electrode layers 12, 16 are formed respectively on
the inside and outside of the piezoelectric layer 14 with leads 20
connected as described above. The transducer is slid along the
instrument shaft to the desired location. This transducer may also
be adapted for use with a balloon, cuffs, elastic bands, etc., as
described above.
Although the core 11 has been described above as relatively rigid,
it should be understood that in alternative embodiments in
accordance with the invention, the core may be any electrically
non-conductive material that reflects rather than transmits or
absorbs the major portion of the ultrasound energy at its interface
with the piezoelectric material and electrodes.
It will thus be seen that the objects set forth above, among those
made apparent from the preceding description, are efficiently
attained and, since certain changes may be made in the above
constructions without departing from the spirit and scope of the
invention, it is intended that all matter contained in the above
description or shown in the accompanying drawings shall be
interpreted as illustrative and not in a limited sense. It should
also be understood that the following claims are intended to cover
all of the generic and specific features of the invention herein
described and all statements of the scope of the invention that may
be said to fall therebetween.
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